Feed-forward recruitment of electrical synapses enhances synchronous spiking in the mouse cerebellar cortex

  1. Andreas Hoehne
  2. Maureen H McFadden
  3. David A DiGregorio  Is a corresponding author
  1. Laboratory of Synapse and Circuit Dynamics, Institut Pasteur, France
  2. Sorbonne University, ED3C, France
8 figures, 1 table and 1 additional file

Figures

Figure 1 with 1 supplement
PF-basket cell (BC) synapse-evoked outward currents that are insensititive to GABAergic receptor antagonists are sensitive to gap junction antagonists.

(A) 2-photon laser scanning microscopy image (2PLSM - maximal intensity projection) of a cerebellar BC patch-loaded with 20 µM Alexa-594. Color arrows indicate the positions of the stimulating …

Figure 1—source data 1

PF-basket cell (BC) synapse-evoked outward currents that are insensititive to GABAergic receptor antagonists are sensitive to gap junction antagonists.

https://cdn.elifesciences.org/articles/57344/elife-57344-fig1-data1-v1.xlsx
Figure 1—figure supplement 1
The amplitude of direct excitatory postsynaptic currents (EPSCs) and outward currents are not correlated.

(A) Average compound synaptic responses recorded at a single site, and at different stimulation intensities, reveal an increase in the amplitude of both the direct EPSC (upper panel) and the …

Figure 1—figure supplement 1—source data 1

The amplitude of direct EPSCs and outward currents are not correlated.

https://cdn.elifesciences.org/articles/57344/elife-57344-fig1-figsupp1-data1-v1.xlsx
Outward currents are reduced in Cx36KO mice and stellate cells (SCs).

(A) Representative traces of PF-mediated synaptic responses recorded in three different conditions (WT P90-150 BCs, P90-150 BCs in Cx36KO mice, and WT P90-150 SCs). Black and colored trace for each …

Figure 2—source data 1

Outward currents are reduced in Cx36KO mice andstellate cells(SCs).

https://cdn.elifesciences.org/articles/57344/elife-57344-fig2-data1-v1.xlsx
Figure 3 with 1 supplement
In the absence of direct excitatory transmission from PFs, GABAergic-independent outward currents are preceded by a short-lasting inward current.

(A) 2PLSM image (maximal intensity projection) of a BC loaded with 20 µM Alexa-594. Dashed white lines indicate the position of the extracellular stimulation electrode on the surface of the slice …

Figure 3—source data 1

In the absence of direct excitatory transmission from PFs, GABAergic-independent outward currents are preceded by a short-lasting inward current.

https://cdn.elifesciences.org/articles/57344/elife-57344-fig3-data1-v1.xlsx
Figure 3—figure supplement 1
Evidence for subthreshold excitatory postsynaptic current (EPSC) transmission across electrical synapses.

(A) 2PLSM image (maximal intensity projection) of a BC loaded with 20 µM Alexa-594. Dashed white lines indicate the position of the extracellular stimulation electrode on top of the slice (off-beam …

Figure 3—figure supplement 1—source data 1

Evidence for subthreshold excitatory postsynaptic currents (EPSC) transmission across electrical synapses.

https://cdn.elifesciences.org/articles/57344/elife-57344-fig3-figsupp1-data1-v1.xlsx
Figure 4 with 1 supplement
Electrical coupling strength between BCs correlates with spikelet amplitude.

(A) 2PLSM image (maximal intensity projection) of two BCs loaded with 20 µM Alexa 594 (red), or 20 µm Alexa 488 (green) using dual whole-cell patch clamp. (B) Membrane potential of both cells (same …

Figure 4—source data 1

Electrical coupling strength between BCs correlates with spikelet amplitude.

https://cdn.elifesciences.org/articles/57344/elife-57344-fig4-data1-v1.xlsx
Figure 4—figure supplement 1
Relationship between coupling coefficients and spikelet transmission, and distance-independence of electrical coupling.

(A) Fraction of BC pairs that are considered ‘connected’ according to different coupling coefficient (CC) thresholds. The dotted red lines indicate the observed frequency of detectable spikelet …

Figure 4—figure supplement 1—source data 1

Relationship between coupling coefficients and spikelet transmission, and distance-independence of electrical coupling.

https://cdn.elifesciences.org/articles/57344/elife-57344-fig4-figsupp1-data1-v1.xlsx
Presynaptic resting potential influences polarity of spikelets.

(A) Action potential from one cell of a paired BC recording (left; holding potential = −70 mV) and corresponding spikelets current recorded in a voltage-clamped postsynaptic cell at different …

Figure 5—source data 1

Presynaptic resting potential influences polarity of spikelets.

https://cdn.elifesciences.org/articles/57344/elife-57344-fig5-data1-v1.xlsx
Figure 6 with 1 supplement
Electrical synapses are more frequent than chemical inhibitory synapses between BCs.

(A) 2P-LSM image (maximal intensity projection) of two BCs loaded with 20 µM Alexa 594 (red) or 20 µm Alexa 488 (green). (B) Representative examples of each of the 3 types of unidirectional …

Figure 6—source data 1

Electrical synapses are more frequent than chemical inhibitory synapses between BCs.

https://cdn.elifesciences.org/articles/57344/elife-57344-fig6-data1-v1.xlsx
Figure 6—figure supplement 1
Identification of GABAergic connections in BC paired recordings.

(A) Table summarizing how often each of three methods were used to detect chemical inhibitory synapses in paired BC recordings: (1) presence of outward current without inward component (i.e. …

Figure 6—figure supplement 1—source data 1

Identification of GABAergic connections in BC paired recordings.

https://cdn.elifesciences.org/articles/57344/elife-57344-fig6-figsupp1-data1-v1.xlsx
Figure 7 with 1 supplement
Feed-forward (FF) recruitment of spikelets narrows excitatory postsynaptic potential (EPSP) width and dampens temporal summation.

(A) Top, voltage-clamp recordings of PF-mediated synaptic responses in a representative BC in response to low stimulation intensity (LS – blue traces) and high stimulation intensity (HS – red …

Figure 7—source data 1

Feed-forward(FF)recruitment of spikelets narrowsexcitatory postsynaptic potential (EPSP)width and dampens temporal summation.

https://cdn.elifesciences.org/articles/57344/elife-57344-fig7-data1-v1.xlsx
Figure 7—figure supplement 1
Control experiments for spikelet effect on excitatory postsynaptic potentials (EPSPs).

(A) The amplitude of the first EPSP is not significantly different between those extracellular stimulation sites where an outward current could be detected (OC, red group, n = 22 sites) and those …

Figure 7—figure supplement 1—source data 1

Control experiments for spikelet effect onexcitatory postsynaptic potentials(EPSPs).

https://cdn.elifesciences.org/articles/57344/elife-57344-fig7-figsupp1-data1-v1.xlsx
Spikelet transmission enables temporal contrast enhancement of basket cell (BC) excitation.

(A) 2PLSM image (maximal intensity projection) of a BC loaded with 20 µM Alexa 594. Dashed lines indicate the position of the stimulating pipettes on top of the slice (off-beam stimulation in red, …

Figure 8—source data 1

Spikelet signaling transmission enables temporal contrast enhancement of basket cell (BC) excitation.

https://cdn.elifesciences.org/articles/57344/elife-57344-fig8-data1-v1.xlsx

Tables

Key resources table
Reagent type
(species) or resource
DesignationSource or referenceIdentifiersAdditional information
Strain, strain background (Mus musculus – male and female)CB6F1Mouse Genome InformaticsRRID:MGI:5649749
Strain, strain background (Mus musculus – male and female)CX36 KO,
129 brown mice (129S1/SvImJ)
David Paul, Harvard UniversityDeans et al. Neuron 2001.The Cx36 coding sequence is replaced by a LacZ-IRES-PLAP reporter cassette
Chemical compound, drugD-AP5AbcamCat#:ab120003
Chemical compound, drugGabazine (SR-95531)AbcamCat#:ab120042
Chemical compound, drugQX-314AbcamCat#:ab120118
Chemical compound, drugNBQXTocrisCat#:1044
Chemical compound, drugAlexa Fluor 488ThermoFisher ScientificCat#:A10436
Chemical compound, drugAlexa Fluor 594ThermoFisher ScientificCat#:A10438
Chemical compound, drugMefloquine hydrochlorideSigma-AldrichCat#:M2319
Chemical compound, drugDMSOSigma-AldrichCat#:D2650
Software, algorithmIgor ProWavemetricsRRID:SCR_000325
Software, algorithmNeuromaticRothman and Silver, 2018; DOI:10.3389RRID:SCR_004186
Software, algorithmImageJNational Institutes of HealthRRID:SCR_003070
Software, algorithmGraphPad Prism 6GraphPad SoftwareRRID:SCR_002798

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